The authors present a preliminary experience with ethyl-enevinylalcohol copolymer (Onyx) for hemangioblastoma vessel embolization before surgical resection. The patient presented with neck pain, dizziness, blurred vision, vomiting, and loss of balance. Diagnostic imaging revealed a posterior fossa cystic mass with a nodular component. Angiography demonstrated a significant vascular blush with arteriovenous shunting that was characteristic of a hemangioblastoma. Tumor vessels originating off the left posterior inferior cerebellar artery were embolized before surgery using Onyx 18 (ev3, Covidien Vascular Therapies, Mansfield, MA, USA). This resulted in complete obliteration of all tumor vessels, transforming a highly vascular tumor into an avascular mass. A safe and uneventful surgical resection was performed the next day. Onyx is a valuable embolic agent for preoperative hemangioblastoma vessel embolization. Because of its low viscosity, Onyx penetrates deeply into the tumor vasculature and allows complete obliteration of tumor vessels. Risks of the intervention have to be carefully weighed against the benefits. If preoperative embolization is indicated, the use of Onyx should be strongly considered.